RE-EXAMINING EVIDENCE FOR FAULTING IN THE WESTERN WICHITA MOUNTAINS, OKLAHOMA

New analysis of geologic, topographic, and geophysical data in the Hale Spring area of the Wichita Mountains suggests that this region is transected by a number of faults, challenging previous faultless interpretations. In particular, results from the SQ-1 borehole (Price et al, 1998), which encountered 87 m of Mt. Scott Granite, were interpreted historically as evidence for a younger age of intrusion for the Sandy Creek Gabbro, which is not supported by current geochronological data. Poorly exposed lithologic contacts between these intrusive units were interpreted as magmatic. We believe linear formational contacts between these units in the Hollis Canyon/Big Four Mountain area define sharp topographic boundaries and mark post-intrusion faults. These faults, variably oriented E-W and NNE-SSW, are inferred to be sub-vertical based on interaction with topography and are poorly constrained in terms of sense and magnitude of displacement. Based on their geometry, we provisionally interpret them as strike-slip faults. One of these, forming the western boundary of Black Bear Mountain, projects just west of the SQ-1 borehole and could explain the absence of the intrusive contact between Mount Scott Granite and Sandy Creek Gabbro. Burial of these faults by the Permian Post Oak Conglomerate implies an upper age limit for their last movement. The presence of these faults appears to be consistent with magnetic surveys collected in connection with the borehole.